If it's been standing there will be a few issues to sort out!
Difficult to value without seeing the thing,but rust is the killer,of course.
Pull back the rtim in the boot on the O/S and have a poke at the rear of the wheel arch...expect a bit of rot just above the rear tow eye,they all do it

but check the rear edge of the box section just in front of the rear valance here as well,not unusual to find this full of water.
Engine's are always fixable,320i's are unloved,but go well if you use the gearbox and let them rev.,it's a short stroke engine so thrives on revs!
Check for oil/water mixing at the oil filler cap and the header tank,it's not the head gasket,it's a cracked head...
Unmetered air leaks on a car that has been standing will give you lots of head-scratching,the big pipe from the AFM to the throttle body will almost certainly need replacing.
Value?
£250-£750.A sound body is all.
Youth is wasted on the young.